One word: "Absolve." At the front desk of the police station. And this is for a sidequest. (Although pulling this off also makes a main quest many times easier.)
Though you shouldn't lean too heavily on it; depending on how he reacts and his mood, this could actually piss him off because you're being sanctimonius.. But yeah, a successful end to that dialogue is very heartwarming.
His responses are actually random. Reload that conversation and you'll get completely different responses. Which actually makes some sense, considering how much stress he's under and the fact that he's on anti-psychotics. No wonder he's got a hair-trigger.
On the whole, if you choose Plead and/or Absolve for the majority of the conversation and choose Crush at the end, telling Haas point-blank that he chose to pull that trigger, no one else, and that he needs to take responsibility for that and put it behind him, you can convince him to turn his life around. Probably because it's the truth, and he knows it: Adam refused to pull that trigger. Haas could have, too. But he didn't. Especially on-point if you manage to hit the dialogue where Wayne tells Adam that he blames Adam for everything that happened, including the fact that Wayne shot the kid. Regardless, hearing him come to the realization that he has to turn his life around is a CMOH as well.
Wayne: Aw, hell... You're right. I've been so stupid! Two whole years... I've gotta start turning things around. Right now.
The monument to those that died in the attack in the opening scenes of the game. It's little touches like these that get people interested in a game's world, after all.
"They shall not grow old as we who are left grow old; Age shall not weary them, nor years condemn." In our hearts and in our minds, their devotion to science will always be remembered. To us, they have found immortality.
Returning Megan's bracelet to her grieving mother.
On a side mission in Detroit during the riots, you find out that you are adopted and that your real parents died in a fire they caused to save you from being used to inoculate other babies in a gene therapy research facility. You find this out from a senile woman who took you from the facility before the fire started. You then have a security detail come to her home to make sure that she is safe,because you consider her family.
That and she gives Adam Christmas and birthday money for all the ones she missed.
Declining the money leads to a additional heartwarming moment. Jenson will decline, stating that she has already done enough for him and is grateful for everything she has done for him.
Jensen's apartment has a table covered in get well soon cards among the bottles and bottles of medicines. It really connects him to the setting and makes it clear that people do care about him.
If you talk to a hobo, one of their random responses is to say "Thanks for talking to me. Most people just walk on by like I'm invisible." Considering most gamers would just ignore every NPC as they went on their way, hearing that is the kind of thing that encourages one to spare the person who said it from their knockout spree.
Malik and her special mission and saving her from death after the plane crash result in heartwarming moments.
"Any time, fly girl."
And a little bit of Fridge Brilliance. There is no way she could have flown 10,000 miles from Detroit in the time from your waking up in Singapore to her reappearance. She stayed in the general vicinity of Hengsha this whole time, waiting for word from you.
Frank's reaction upon first hearing from Adam after a few days of Adam being MIA, along with his genuine concern over Adam being effectively on his own on Panchaea, without Frank as his Mission Control. It's such a huge change from his initial disdain.
Talk to the Sarif employees, including the security and janitorial staff. It's obvious that Adam is well-liked; with very few exceptions, anyone who talks to him about himself either wishes him well, is glad to have him back, feels safer having him around, expresses concern over what he's been through, tells him not to push himself too hard, or some combination of the above.
If you undergo one of the optional quests in Detroit, you'll find out that this extended also to his previous job at the police. After the Mexicantown incident, Adam's higher-ups forced the making of a very negative psych evaluation; the detective investigating Adam's past for Sarif, however, figured that "it reads like fiction" because, upon meeting some former colleagues of Adam, they all expressed appreciation for him; the person forced to write that evaluation even made every effort to keep it concealed.
DavidSarif himself. The guy may make some shady decisions , but he's also the only authority figure in the game who refuses to have anything to do with The Illuminati, and his ultimate goal really is to try to bring augmentation to the masses.
Especially since the 'we' and 'first' in that sentence imply Sarif was planning on coming back personally to help move the rest.
A strange mix of heartwarming and a tearjerker is Pritchard's response to Malik's death, as it really hammers home just how much he haswarmed up to Adam. One person he cared about was just killed; he doesn't want to lose Adam, too.
Adam: Bastards ambushed us, Pritchard! Malik didn't make it!
Frank: Oh. God... I—I know you... might... want to get even. But if they see you; if they recognize you—! It might be better to stay out of their way.
Adams's speech after destroying Panchea, explaining that, while he doesn't really know whether or not humanity can save itself, he believes that basic human decency will hold out, and that it's not up to anyone else but them to build the future; not Sarif, not Darrow, not Taggart, not even himself.
Adam: Do I trust humanity to save itself? That's what Eliza was asking. The truth is, I don't know. After everything I've seen, all the fighting, and the chaos around me, I only know what I want to believe: somehow, Human decency will triumph. These past few months, I've faced many life-threatening situations. I could have given up many times, but my need to know the truth, to uncover the secrets that others were hiding, and to survive forced me to keep on going. Most of the time, I tried to keep my values in mind, knowing my actions did not have to harm others. I held on to my humanity, resisting the urge to abuse power or resources in order to meet my goals. And in the end, I got the job done. But does this mean I have the right to choose for everyone? No. Because it isn't up to me. It isn't up to Darrow, Sarif, or Taggart either. Ordinary men and women will have to decide together what course mankind should take. The kind of people who, time and time again, have picked and chosen the future in highly practical ways -slowing change when it's negative, speeding it up when it's good. Can we do it again? I don't know. But I do know that I'm not about to let anyone in this station, myself included, stand in their way.
Michael Zelazny, in a world of cruel self-serving mercenaries, he and his men are the only ones who joined for the purpose of defending people which is the reason they go rogue from Belltower after finding out that their operations were for corrupt politicians. More here.
If you meet with Zeke, he'll have a couple of Purity First members with him. One of them you can talk to apparently set up the bomb meant to kill the hostages in the Sarif manufacturing plant. If you failed to save the hostages then he'll gloat about how his gas disperser killed them all, and most likely cause you to open fire on the three of them. But if you managed to save the hostages, then he'll tell you that he's glad you managed to do so.